S. Mandayam/ ECOMMS/ECE Dept./Rowan University Electrical Communications Systems Spring 2005 Shreekanth Mandayam ECE Department Rowan University Lab 3: Pre-lab Instruction

S. Mandayam/ ECOMMS/ECE Dept./Rowan University ECOMMS: Topics

S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversityPlan FM Signal and Spectrum FM Detection Slope Detector FM Generation Voltage Controlled Oscillator (VCO) Phase Locked Loop (PLL) FM Detection Lab Project 3

S. Mandayam/ ECOMMS/ECE Dept./Rowan University FM Signal & Spectrum Single-tone FM Signal Single-tone FM Spectrum 0 f c -3f m f c -2f m f c -f m f c f c +f m f c +2f m f c +3f m |S(f)| / (A c /2) f J0()J0() J1()J1() J2()J2() J3()J3()

S. Mandayam/ ECOMMS/ECE Dept./Rowan University FM Detection FM Signal, We need a frequency-voltage converter Slope Detector

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Slope Detector AM Detector Frequency- voltage converter LPF Envelope Detector |H(f)| f t f i (t) v o (t)

S. Mandayam/ ECOMMS/ECE Dept./Rowan University FM Generation Voltage Controlled Oscillator f 0 =f c m(t)m(t) Control Voltage Instantaneous Frequency

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Oscillators: Principle A   Signal Source Amplifier Feedback Network Output + - vivi vsvs vovo Barkhausen Criteria for oscillation : A  = -1

S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversityOscillators Schmitt Trigger Oscillator Waveforms

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Intersil 8038 Precision Waveform Generator/Voltage Controlled Oscillator v 10 t V c1 V c2 Switch Open, C charges Switch Closed, C discharges Flip-Flop Changes State

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Phase Locked Loop Phase Detector VCO LPF A fifi f vco f i -f vco Loop Filter vovo f fofo Capture Range, f C Hold (lock) Range, f H

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Lab Project 3: Frequency Modulation and Detection

S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversitySummary